Question

reactivity of 7a group elements

Answer 1

hi there,
group 7 elements are fluorine  chlorine  bromine iodine and astatine.
 in these  fluorine is that most reactive  followed  by chlorine , bromine  iodine and astatine.
i hope this helps u...

Answer 2

Group 7 elements have 7 electrons in their outermost shell. They can accept one electron.
Since the affinity to accept electron is more when size of the atom is less, fluorine is the most reactive in the group and the reactivity decreases down the group. The reactivity is in the order 
Fluorine > Chlorine > Bromine > Iodine